Field of Invention
The invention relates to a ventilation fan.
Related Art
With the progress of technologies, people place more importance on the life quality than before, especially on the air quality and human health. However, for the sake of blocking the outdoor noise and heat and remaining the indoor temperature, the buildings are usually constructed by special materials to create unventilated rooms. Accordingly, the ventilation is insufficient and the harmful contaminations can't be exhausted.
Therefore, it is an important subject to provide a ventilation fan which can keep the indoor ventilation.